NASA has selected a Planetary Science Institute-led proposal to investigate whether a potentially large underground cave extends beyond the opening of a lunar pit. Such a cave may one day provide a safe haven for astronauts to escape the radiation and extreme temperature swings present at the lunar surface. The project will be funded through NASA’s Payloads and Research Investigations on the Surface of the Moon (PRISM) program, which sends scientific instruments to the Moon on spacecraft provided by the Commercial Lunar Payloads Services (CLPS) initiative providers.
Led by PSI Associate Director and Senior Scientist Than Putzig , the selected project is the Geophysical Instruments for Marius Lunar pit Investigation, or GIMLI. PSI is partnering with Honeybee Robotics on the effort, who will build much of the equipment and instrumentation, which will be carried on a CLPS initiative provided lander and rover. The PSI work will be carried out in partnership with the Norwegian Space Agency.
“GIMLI represents the type of ambitious planetary science that PSI was built to pursue,” said PSI Director and CEO Amanda Hendrix . “Than and his team are taking a scientific question we’ve been studying from orbit and have developed a way to investigate it directly on the Moon. We’re excited to have PSI leading this effort and to be partnering with NASA and Honeybee Robotics to learn more about the Moon and its volcanic past.”
Observations from lunar orbit have provided compelling evidence that caves and lava tubes may exist under the Moon’s surface. GIMLI’s research will focus on the Marius Hill Pit (MHP), a large hole in one of the Moon’s most volcanically diverse regions. Like other lunar pits, MHP may serve as an opening to these underground spaces, which may have formed during ancient volcanic activity.
GIMLI will allow scientists to investigate MHP directly from the lunar surface.
“It’s long been a desire of mine to reintroduce intentional active-source seismic methods to planetary science, as it has essentially not been done since the Apollo astronauts conducted the first seismic surveys on the Moon,” shared Putzig. “Combining that method with ground-penetrating radar and gravity measurements makes it all the more exciting, as these methods together will allow us to get a much better understanding of subsurface properties — including the anticipated detection of a lava tube extending away from the Marius Hills pit.”
GIMLI will use tools including ground-penetrating radar, seismic sensors, and a gravimeter to look beneath the surface, with cameras providing imagery of the surface and pit walls. Together, these instruments will not only search for an underground void extending from MHP, but if one exists, they will also help determine its size.
Honeybee Robotics, a Blue Origin company, will serve as a commercial partner to PSI, providing project management services and building the instrumentation for the active-source seismic system, gravimeter, and cameras. They will also work to integrate all instruments onto the lander and rover and, together with PSI, will lead their operations on the lunar surface.
Even if GIMLI does not find a cave or lava tube beneath the surface, the results and data could still help answer an important question: How did the pit form? Measurements of the surrounding subsurface could help answer questions around the origin of MHP, as well as providing a better understanding of the geology and volcanic history around the site.
The GIMLI team will also look beyond the pit itself. The geographic area has a long history of volcanic activity, and MHP walls expose layers of regolith and lava flows that are usually hidden underground. Studying those layers could reveal how lava traveled on the Moon and whether long periods of time separated eruptions.
Lunar pits are of interest for more than the geology preserved in their walls. The interiors of any potential underground spaces could also preserve a history of the volcanic processes that shaped the Moon.
“Confirming a substantial lava tube would give us an insight into how volcanism operated on the Moon,” explained Gareth Morgan , PSI Senior Scientist and Deputy Principal Investigator on the GIMLI program. “Lava tubes are a common feature of basaltic volcanism on Earth, so identifying them on the Moon means we could use knowledge of such terrestrial caves to better understand lunar history.”
Beyond PSI and Honeybee Robotics, the team includes Co-Investigators from Boise State University, Johns Hopkins University, the Lunar and Planetary Institute, and the University of Oslo, with the ground penetrating radar being provided by the Norwegian Space Agency.
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